Background: Previous reports suggest that ischemic conditions rapidly reduce the capacity of human albumin to bind exogenous cobalt. A new assay based on human albumin-cobalt binding (ACB) may help detect early myocardial ischemia. We investigated altered ACB during the first 24 hours after transient ischemia induced during elective percutaneous transluminal coronary angioplasty (PTCA). We then compared ACB assay results with creatine kinase isoenzyme (CK-MB), myoglobin, and cardiac troponin I (cTn-I) values after PTCA.
Methods and results: In 41 patients undergoing elective PTCA, plasma samples were tested for the ACB assay, CK-MB, myoglobin, and cTn-I before, immediately after, and 6 and 24 hours after PTCA. Thirteen additional patients served as a control group with albumin-cobalt assays performed before and after diagnostic coronary catheterization without angioplasty. ACB assay results demonstrated a significant mean percent difference (10.1%) immediately after PTCA compared with baseline (P < .000001) and returned to baseline by 6 hours after PTCA. ACB assay differences immediately after PTCA were significantly greater than in the control group (10.1% vs -0.9%, P < .001). Mean CK-MB, myoglobin, and cTn-I values were not elevated above baseline immediately after PTCA but were significantly elevated above baseline 6 and 24 hours after PTCA.
Conclusions: These preliminary results suggest that human albumin undergoes a significant reduction in its capacity to bind exogenous cobalt soon after transient coronary occlusion during human PTCA and before significant elevations of CK-MB, myoglobin, or cTn-I. Further confirmatory investigations are warranted to determine if the ACB assay is a useful diagnostic test for early myocardial ischemia.